REFLECTANCE INFRARED SPECTROSCOPIC ANALYSIS OF MONOLAYER FILMS AT THEAIR-WATER-INTERFACE

The transition moment direction and absorbance are reported for the CH 2 stretching vibrations of H(CH2) (18)-OH (I) at 2918 and 2850 cm(-1) and for the CF2 stretching vibrations of F(CF2)(10)-(CH2)(2)-OH (II) a t 1151 and 1207 cm(-1) in densely packed monolayers at an air/water in terface. Packing was monitored by measuring force-area relations for t he two systems. Absorbance and transition moment direction parameters are given as estimated by fitting observed s-polarized reflectance spe ctra obtained as a function of incidence angle to calculated theoretic al reflectance spectra by minimum least-squares difference. The parame ters determined from s-polarized reflectance spectra were used to calc ulate p-polarized reflectance spectra. The results compared well with experimental observations of p-polarized reflectance spectra. The resu lts suggest that, at the packing densities used, the chain axis orient ations are 12.9 degrees and 0 degrees for I and II, respectively.